646740 has 36 divisors (see below), whose sum is σ = 1962324. Its totient is φ = 172416.

The previous prime is 646721. The next prime is 646757. The reversal of 646740 is 47646.

It can be written as a sum of positive squares in 2 ways, for example, as 219024 + 427716 = 468^2 + 654^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a nialpdrome in base 15.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1617 + ... + 1976.

It is an arithmetic number, because the mean of its divisors is an integer number (54509).

2⁶⁴⁶⁷⁴⁰ is an apocalyptic number.

646740 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

646740 is an abundant number, since it is smaller than the sum of its proper divisors (1315584).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646740 is a wasteful number, since it uses less digits than its factorization.

646740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3608 (or 3603 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 646740 is about 804.2014672954. The cubic root of 646740 is about 86.4788503428.

The spelling of 646740 in words is "six hundred forty-six thousand, seven hundred forty".